This invention relates generally as indicated to a valve and method of making such a valve and more particularly to a three-way valve in which a unitary bobbin/valve body provides the entire support structure for the solenoid and the plunger and defines all of the valve""s inlet/outlet ports.
A valve typically includes a plurality of ports through which fluid is selectively passed to accomplish a desired flow path. For example, a three-way valve may include a common port, a normally open port, and a normally closed port. When the valve is in an inactivated state, fluid enters the valve through the common port and exits through the normally open port. When the valve is in an activated state, fluid enters the valve through the common port and exits through the normally closed port.
A three-way valve may include a solenoid and a plunger that is used to shift the valve between its inactivated and activated states. Such a solenoid comprises components which generate and transmit a magnetic field. Specifically, a solenoid may include a solenoid coil which generates a magnetic field upon application of an electrical current and this magnetic field is transmitted to a pole piece. Terminal pins are typically provided to selectively energize the solenoid coil and a flux conductor is typically provided to concentrate magnetic flux in a desired manner.
A plunger commonly comprises a plunger body or armature which directs the flow through the valve in response to the energization/deenergization of the solenoid. A spring or other type of biasing assembly is typically provided to bias the plunger body towards a position whereat it seals off the passageway to the normally closed port and not the normally open port. When the solenoid is energized, the plunger body is pulled towards the pole piece by the magnetic force (that overcomes the spring biasing force) to a position whereat it seals off the passageway to the normally open port and not the normally closed port.
A three-way solenoid valve commonly includes a bobbin and one or more valve body pieces which together define the ports and which together provide a support structure for the solenoid and the plunger. The coupling of the bobbin and the valve body piece(s) together requires separate assembly steps and/or special coupling components. Moreover, the unions between the bobbin and the valve body piece(s) introduce leakage issues sometimes requiring separate inspection tests during assembly of the valve.
Three-way valves are used for a wide variety of industrial, medical, and other types of analytical systems. Different types of valve mounting arrangements are often required depending on the particular system. For example, some applications require a manifold mounted arrangement and other applications require a printed circuit board arrangement. Furthermore, different orientations of the valve ports are often required in different plumbing settings. Additionally or alternatively, it is often necessary (or at least desired) to have a two dimensional array of valves mounted on the same manifold and/or printed circuit board.
In many valve applications, dimensions are crucial and constant efforts are being made to reduce the size of valve assemblies. However, while size reduction is desirable, it often comes at the expense of more complicated assembly techniques and/or elevated manufacturing costs. Furthermore, the smallness of the bobbin and/or the valve body piece(s) tends to increase leakage issues during assembly due to, among other things, the tight tolerances involved. Additionally or alternatively, size reduction often results in the sacrifice of some desirable features, such as adjustability of valve seat sealing characteristics and/or electrical terminal options. Moreover, valve size reduction is sometimes difficult to accomplish within reasonable economic ranges and thus such reduction is of little benefit in many cost-sensitive valving situations.
Accordingly, the inventors appreciated that a need remains for compact and versatile valves that may be made by simplified assembly techniques and within reasonable economic ranges, without significant leakage issues.
The present invention provides a valve that may be manufactured and assembled in a relatively simplified and economic manner. Additionally, the valve""s design is such that leakage issues are minimized and the valve may be used for a wide variety of industrial, medical and/or analytical systems without requiring different valve constructions. Further, a preferred form of the valve allows for adjustment of valve seat sealing characteristics (by changing the biasing force on the spring) and/or is compatible with different orientations of terminal pins. The valve may be produced in a very compact size thereby making it suitable for applications requiring small scale valving apparatus. However, the valve design of the present invention has many features equally advantageous in larger scale valving apparatus and thus the valve could be made in wide variety of dimensions.
More particularly, the present invention provides a valve comprising a bobbin/valve body, a solenoid, and a plunger. The bobbin/valve body is formed in one piece and defines a common port, a normally closed port, a normally open port, a longitudinal bore, and respective passageways between the longitudinal bore and the ports. The bobbin/valve body provides the entire support structure for the solenoid and the plunger whereby assembly and inspection steps associated with joining together separate bobbin and valve body piece(s) are eliminated. For this same reason, leakage issues may be significantly reduced. Additionally, the preferred bobbin/valve body may be made by economic mass manufacturing methods thereby further reducing manufacturing costs. Furthermore, a valve construction wherein a one-piece bobbin/valve body defines at least the normally open port (and not necessarily the common port or the normally closed port) is believed to in and of itself reduce the size of the valve.
The bobbin/valve body preferably comprises an end portion defining the normally open port, another end portion defining the common and normally closed ports, and a cylindrical central portion therebetween. The common port, the normally closed port, and the normally open port are preferably aligned with each other in the axial direction of the longitudinal bore thereby making the valve compatible with a variety of different mounting arrangements. For example, the valve is especially suitable for manifold mounting and to this end barbs are preferably provided on the port nipples to allow with-seal or without-seal coupling to the manifold channels. The valve is also especially suitable for mounting on a printed circuit board and to this end the exterior walls of the bobbin/valve body preferably include slots, grooves, and/or recesses to accommodate appropriate mounting elements (e.g., mounting wires, screws, clips, etc.).
The plunger includes a plunger body which moves within the longitudinal bore of the bobbin/valve body in response to the energization/deenergization of the solenoid. Specifically, the plunger body moves between a first position whereat the passageway to the normally closed port is sealed and the passageway to the normally open port is open and a second position whereat the passageway to the normally closed port is open and the passageway to the normally open port is sealed. In this manner, fluid flows through the common port to the normally open port when the plunger body is in the first position and through the common port to the normally closed port when the plunger body is in the second position. Preferably, the plunger body is moved to the second position upon energization of the solenoid.
The solenoid preferably includes a pole piece positioned within the longitudinal bore and the pole piece preferably defines a passageway from the bobbin/valve body""s passageway to the normally open port. This passageway extends through an opening in an axial end of the pole piece and a valve seat surrounds this opening. Another valve seat (defined by the bobbin/valve body) surrounds the passageway from the longitudinal bore to the normally closed port. The plunger body seals the body""s valve seat when in one of its first and second positions and seals the pole""s valve seat when in the other position. Preferably, the plunger body seals the body""s valve seat when in its first position (when the solenoid is deenergized) and seals the pole""s valve seat when in its second position (when the solenoid is energized).
The plunger body and/or the bobbin/valve body preferably includes longitudinal ribs that extend radially to define flow channels between the plunger body and the bobbin/valve body. Preferably, the longitudinal bore of the bobbin/valve body includes a ribbed section including the ribs and the passageway between the longitudinal bore and the common port communicates with this ribbed section. The pole""s passageway preferably includes a longitudinal passageway and a radial passageway. The longitudinal passageway extends from the valve seat to the radial passageway and the radial passageway communicates with the bobbin/valve body""s passageway to the normally open port. Flow introduced through the common port passes through the relevant passageway to the longitudinal bore and into the rib-defined flow channel towards the pole""s valve seat. When the solenoid is deenergized (or unenergized), and the plunger body is in its first position, the pole""s valve seat is open and the fluid flows through the pole""s longitudinal and radial passageways to the normally open port.
The passageway between the longitudinal bore and the normally closed port includes a cross-over passageway extending axially outward from the body""s valve seat and a passageway extending perpendicularly from the cross-over passageway to the normally closed port. When the solenoid is energized, and the plunger body is in its second position, the pole""s valve seat is sealed and the body""s valve seat is opened. Fluid thus passes from the longitudinal bore through the passageways to the normally closed port. Upon deenergization of the solenoid, the plunger body is moved back to the first position whereby fluid flows through the pole passageways to the normally open port.
The plunger preferably includes a spring that biases the plunger body towards the normally closed valve seat (in the bobbin/valve body) and a spring retainer that holds the spring in the desired biasing relationship. The spring is preferably a cylindrical spring that circumferentially surrounds the plunger body and the spring retainer is preferably a ring-shaped member secured radially inward of the flow channel-defining ribs. This arrangement of the spring relative to the plunger body allows a reduction in overall length of the valve when compared to, for example, a valve design wherein a spring is positioned axially in line with the plunger body. Also, this arrangement of the spring and spring retainer allows for adjustment of the valve seat sealing characteristics by adjusting the position of the spring retainer and thus the biasing force of the spring.
To assemble the valve according to the present invention, the bobbin/valve body is formed in one piece, preferably by an economic mass manufacturing process, such as injection molding. The plunger body is inserted through an end opening in the bobbin/valve body into the longitudinal bore. The spring is situated around the plunger body and the spring retainer is attached to the bobbin/valve body, preferably by press-fitting, to hold the spring in the desired biasing position. After insertion of the plunger components, the pole piece is inserted through the opening into the longitudinal bore and attached to the bobbin/valve body. A solenoid coil is wound around the central cylindrical section of the bobbin/valve body and the terminal pins are attached to the body in such a manner that they are in contact with the solenoid coil. A flux conductor (preferably of a one-piece construction) is then attached to the bobbin/valve body and the pole piece to complete the assembly of the valve. Preferably, the attachment of the spring retainer, the pole piece, terminal pins and/or the flux conductor is accomplished by a press-fit coupling arrangement. Thus, no additional coupling components, materials and/or steps (e.g., welds, adhesives, etc.) are required thereby simplifying assembly techniques and reducing manufacturing costs.
With particular reference to the terminal pins, the preferred attachment technique includes inserting sections of the pins through openings in the bobbin/valve body and placing end sections in contact with the solenoid coil. The xe2x80x9cnon-insertedxe2x80x9d sections of the pins may be bent into the desired orientation. In this manner, different types of terminal pins may be incorporated into the valve and/or the same terminal pins may be trimmed or otherwise bent to accommodate different mounting arrangements.
It may be noted that one or more of the desired features of the invention may be combined to create a valve of a desired construction. For example, a bobbin/valve body (one piece or otherwise) having a flat exterior mounting surface (except for the port nipples) is believed to be advantageous in and of itself in view of its compatibility with different manifold/board mounting arrangements. A valve construction wherein the solenoid coil surrounds both the plunger body and the pole piece and/or a flux conductor which straddles an axial section of the bobbin/valve body including both the common port and the normally open port is beneficial in view of the potential for overall length-reduction of the valve. Furthermore, a valve incorporating the press-fit attachment of the terminal pins, and the ability to bend them to accommodate different mounting arrangements, provides advantages with or without the other preferred features of the invention.
Thus, the present invention provides a compact and versatile valve that may be made by simplified assembly techniques and within reasonable economic ranges, without significantly increasing leakage issues. These and other features of the invention are fully described and particularly pointed out in the claims. The following description and drawings set forth in detail a certain illustrative embodiment of the invention, these embodiments being indicative of but one of the various ways in which the principles of the invention may be employed.